Azure#63 solved the problem, with base64 library.

Author: katmsft

lib/azure/core/auth/signer.rb

@@ -32,7 +32,7 @@ def initialize(access_key)
             raise ArgumentError, 'Signing key must be provided'
           end
 
-          @access_key = Base64.strict_decode64(access_key)
+          @access_key = Base64.decode64(access_key)
         end
 
         # Generate an HMAC signature.